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qemu-e2k/hw/i2c/smbus.c
Corey Minyard d307c28ca9 i2c: Allow I2C devices to NAK start events 
Add a return value to the event handler.  Some I2C devices will
NAK if they have no data, so allow them to do this.  This required
the following changes:

Go through all the event handlers and change them to return int
and return 0.

Modify i2c_start_transfer to terminate the transaction on a NAK.

Modify smbus handing to not assert if a NAK occurs on a second
operation, and terminate the transaction and return -1 instead.

Add some information on semantics to I2CSlaveClass.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2017-01-09 11:40:20 +00:00

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/*
* QEMU SMBus device emulation.
*
* Copyright (c) 2007 CodeSourcery.
* Written by Paul Brook
*
* This code is licensed under the LGPL.
*/
/* TODO: Implement PEC. */
#include "qemu/osdep.h"
#include "hw/hw.h"
#include "hw/i2c/i2c.h"
#include "hw/i2c/smbus.h"
//#define DEBUG_SMBUS 1
#ifdef DEBUG_SMBUS
#define DPRINTF(fmt, ...) \
do { printf("smbus(%02x): " fmt , dev->i2c.address, ## __VA_ARGS__); } while (0)
#define BADF(fmt, ...) \
do { fprintf(stderr, "smbus: error: " fmt , ## __VA_ARGS__); exit(1);} while (0)
#else
#define DPRINTF(fmt, ...) do {} while(0)
#define BADF(fmt, ...) \
do { fprintf(stderr, "smbus: error: " fmt , ## __VA_ARGS__);} while (0)
#endif
enum {
SMBUS_IDLE,
SMBUS_WRITE_DATA,
SMBUS_RECV_BYTE,
SMBUS_READ_DATA,
SMBUS_DONE,
SMBUS_CONFUSED = -1
};
static void smbus_do_quick_cmd(SMBusDevice *dev, int recv)
{
SMBusDeviceClass *sc = SMBUS_DEVICE_GET_CLASS(dev);
DPRINTF("Quick Command %d\n", recv);
if (sc->quick_cmd) {
sc->quick_cmd(dev, recv);
}
}
static void smbus_do_write(SMBusDevice *dev)
{
SMBusDeviceClass *sc = SMBUS_DEVICE_GET_CLASS(dev);
if (dev->data_len == 0) {
smbus_do_quick_cmd(dev, 0);
} else if (dev->data_len == 1) {
DPRINTF("Send Byte\n");
if (sc->send_byte) {
sc->send_byte(dev, dev->data_buf[0]);
}
} else {
dev->command = dev->data_buf[0];
DPRINTF("Command %d len %d\n", dev->command, dev->data_len - 1);
if (sc->write_data) {
sc->write_data(dev, dev->command, dev->data_buf + 1,
dev->data_len - 1);
}
}
}
static int smbus_i2c_event(I2CSlave *s, enum i2c_event event)
{
SMBusDevice *dev = SMBUS_DEVICE(s);
switch (event) {
case I2C_START_SEND:
switch (dev->mode) {
case SMBUS_IDLE:
DPRINTF("Incoming data\n");
dev->mode = SMBUS_WRITE_DATA;
break;
default:
BADF("Unexpected send start condition in state %d\n", dev->mode);
dev->mode = SMBUS_CONFUSED;
break;
}
break;
case I2C_START_RECV:
switch (dev->mode) {
case SMBUS_IDLE:
DPRINTF("Read mode\n");
dev->mode = SMBUS_RECV_BYTE;
break;
case SMBUS_WRITE_DATA:
if (dev->data_len == 0) {
BADF("Read after write with no data\n");
dev->mode = SMBUS_CONFUSED;
} else {
if (dev->data_len > 1) {
smbus_do_write(dev);
} else {
dev->command = dev->data_buf[0];
DPRINTF("%02x: Command %d\n", dev->i2c.address,
dev->command);
}
DPRINTF("Read mode\n");
dev->data_len = 0;
dev->mode = SMBUS_READ_DATA;
}
break;
default:
BADF("Unexpected recv start condition in state %d\n", dev->mode);
dev->mode = SMBUS_CONFUSED;
break;
}
break;
case I2C_FINISH:
switch (dev->mode) {
case SMBUS_WRITE_DATA:
smbus_do_write(dev);
break;
case SMBUS_RECV_BYTE:
smbus_do_quick_cmd(dev, 1);
break;
case SMBUS_READ_DATA:
BADF("Unexpected stop during receive\n");
break;
default:
/* Nothing to do. */
break;
}
dev->mode = SMBUS_IDLE;
dev->data_len = 0;
break;
case I2C_NACK:
switch (dev->mode) {
case SMBUS_DONE:
/* Nothing to do. */
break;
case SMBUS_READ_DATA:
dev->mode = SMBUS_DONE;
break;
default:
BADF("Unexpected NACK in state %d\n", dev->mode);
dev->mode = SMBUS_CONFUSED;
break;
}
}
return 0;
}
static int smbus_i2c_recv(I2CSlave *s)
{
SMBusDevice *dev = SMBUS_DEVICE(s);
SMBusDeviceClass *sc = SMBUS_DEVICE_GET_CLASS(dev);
int ret;
switch (dev->mode) {
case SMBUS_RECV_BYTE:
if (sc->receive_byte) {
ret = sc->receive_byte(dev);
} else {
ret = 0;
}
DPRINTF("Receive Byte %02x\n", ret);
dev->mode = SMBUS_DONE;
break;
case SMBUS_READ_DATA:
if (sc->read_data) {
ret = sc->read_data(dev, dev->command, dev->data_len);
dev->data_len++;
} else {
ret = 0;
}
DPRINTF("Read data %02x\n", ret);
break;
default:
BADF("Unexpected read in state %d\n", dev->mode);
dev->mode = SMBUS_CONFUSED;
ret = 0;
break;
}
return ret;
}
static int smbus_i2c_send(I2CSlave *s, uint8_t data)
{
SMBusDevice *dev = SMBUS_DEVICE(s);
switch (dev->mode) {
case SMBUS_WRITE_DATA:
DPRINTF("Write data %02x\n", data);
dev->data_buf[dev->data_len++] = data;
break;
default:
BADF("Unexpected write in state %d\n", dev->mode);
break;
}
return 0;
}
static int smbus_device_init(I2CSlave *i2c)
{
SMBusDevice *dev = SMBUS_DEVICE(i2c);
SMBusDeviceClass *sc = SMBUS_DEVICE_GET_CLASS(dev);
return sc->init(dev);
}
/* Master device commands. */
int smbus_quick_command(I2CBus *bus, uint8_t addr, int read)
{
if (i2c_start_transfer(bus, addr, read)) {
return -1;
}
i2c_end_transfer(bus);
return 0;
}
int smbus_receive_byte(I2CBus *bus, uint8_t addr)
{
uint8_t data;
if (i2c_start_transfer(bus, addr, 1)) {
return -1;
}
data = i2c_recv(bus);
i2c_nack(bus);
i2c_end_transfer(bus);
return data;
}
int smbus_send_byte(I2CBus *bus, uint8_t addr, uint8_t data)
{
if (i2c_start_transfer(bus, addr, 0)) {
return -1;
}
i2c_send(bus, data);
i2c_end_transfer(bus);
return 0;
}
int smbus_read_byte(I2CBus *bus, uint8_t addr, uint8_t command)
{
uint8_t data;
if (i2c_start_transfer(bus, addr, 0)) {
return -1;
}
i2c_send(bus, command);
if (i2c_start_transfer(bus, addr, 1)) {
i2c_end_transfer(bus);
return -1;
}
data = i2c_recv(bus);
i2c_nack(bus);
i2c_end_transfer(bus);
return data;
}
int smbus_write_byte(I2CBus *bus, uint8_t addr, uint8_t command, uint8_t data)
{
if (i2c_start_transfer(bus, addr, 0)) {
return -1;
}
i2c_send(bus, command);
i2c_send(bus, data);
i2c_end_transfer(bus);
return 0;
}
int smbus_read_word(I2CBus *bus, uint8_t addr, uint8_t command)
{
uint16_t data;
if (i2c_start_transfer(bus, addr, 0)) {
return -1;
}
i2c_send(bus, command);
if (i2c_start_transfer(bus, addr, 1)) {
i2c_end_transfer(bus);
return -1;
}
data = i2c_recv(bus);
data |= i2c_recv(bus) << 8;
i2c_nack(bus);
i2c_end_transfer(bus);
return data;
}
int smbus_write_word(I2CBus *bus, uint8_t addr, uint8_t command, uint16_t data)
{
if (i2c_start_transfer(bus, addr, 0)) {
return -1;
}
i2c_send(bus, command);
i2c_send(bus, data & 0xff);
i2c_send(bus, data >> 8);
i2c_end_transfer(bus);
return 0;
}
int smbus_read_block(I2CBus *bus, uint8_t addr, uint8_t command, uint8_t *data)
{
int len;
int i;
if (i2c_start_transfer(bus, addr, 0)) {
return -1;
}
i2c_send(bus, command);
if (i2c_start_transfer(bus, addr, 1)) {
i2c_end_transfer(bus);
return -1;
}
len = i2c_recv(bus);
if (len > 32) {
len = 0;
}
for (i = 0; i < len; i++) {
data[i] = i2c_recv(bus);
}
i2c_nack(bus);
i2c_end_transfer(bus);
return len;
}
int smbus_write_block(I2CBus *bus, uint8_t addr, uint8_t command, uint8_t *data,
int len)
{
int i;
if (len > 32)
len = 32;
if (i2c_start_transfer(bus, addr, 0)) {
return -1;
}
i2c_send(bus, command);
i2c_send(bus, len);
for (i = 0; i < len; i++) {
i2c_send(bus, data[i]);
}
i2c_end_transfer(bus);
return 0;
}
static void smbus_device_class_init(ObjectClass *klass, void *data)
{
I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
sc->init = smbus_device_init;
sc->event = smbus_i2c_event;
sc->recv = smbus_i2c_recv;
sc->send = smbus_i2c_send;
}
static const TypeInfo smbus_device_type_info = {
.name = TYPE_SMBUS_DEVICE,
.parent = TYPE_I2C_SLAVE,
.instance_size = sizeof(SMBusDevice),
.abstract = true,
.class_size = sizeof(SMBusDeviceClass),
.class_init = smbus_device_class_init,
};
static void smbus_device_register_types(void)
{
type_register_static(&smbus_device_type_info);
}
type_init(smbus_device_register_types)
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